For an image forming apparatus, such as a copier, a printer, a facsimile, and a compound machine thereof, a scheme has been known such that, for example, a developing device, a charging device, and a photoconductor are integrally formed as an image forming unit, and the image forming unit is detachably attached to the image forming apparatus. Such a scheme has been adopted for many products because of its advantage that maintenance of the apparatus can be easily performed by replacing the unit with another one by a user. Types of such an image forming unit include an image forming unit where a developer container for containing developer, such as toner, is integrally formed with the image forming unit, and an image forming unit where a developer container is separately formed from the image forming unit.
For the case of the former, when the stored developer runs out, the image forming unit is replaced with a new unit. This case is advantageous in that the developing device and the photoconductor can be replaced together with the used developer container, and thereby easing the replacement tasks.
On the other hand, for the case of the latter, when the stored developer runs out, only the developer container is replaced with a new one. In this case, the developing device and the photoconductor can be continuously used without being replaced, provided that their longevities have not been reached. Backed by an increasing interest in consideration of environmental impact, the configuration where the developer container can separately be replaced is becoming the mainstream.
In the configuration where the developer container is separately attached and detached, it may be required to position a position of a discharge opening of the developer container with a position of a supply opening of the developing device. Therefore, in general, a guide unit for guiding the developer container during attaching or detaching the developer container and a positioning portion for positioning the developer container with respect to the main body of the image forming apparatus are provided on the exterior surface of the developer container.
Further, there is a developer container that includes a conveyance screw for conveying the developer inside the developer container and an agitator for agitating the developer. In such a developer container, a driving force to the conveyance screw and the agitator is generally obtained from a driving source disposed in the main body of the image forming apparatus. Therefore, gears are provided on the exterior of such type of a developer container, so as to transfer the driving force from the driving source in the main body of the image forming apparatus to the conveyance screw and the agitator (cf., Patent Document 1 (Japanese Registered Patent No. 4283070) and Patent Document 2 (Japanese Patent Laid-Open Application No. 2006-139069)).
When the gears are provided on the exterior of the developer container as described above, it may be required to prevent the guide unit for guiding the developer container during attaching or detaching of the developer container from interfering with the gears. Therefore, there is a restriction on the layout that the guide unit attached to the developer container is placed at a position that is separated from a position where the gears are provided. In this case, the size of the developer container becomes large accordingly. Therefore, there is a problem that it is difficult to downsize the device.
In view of the above problem, an object of the present invention is to provide a developer container that improves a degree of freedom in designing a layout of a guide unit that can be downsized, and a developing device, a process unit, and an image forming apparatus that include the developer container.